In recent years, jet-propulsion personal watercraft (PWC) have been widely used in leisure, sport, rescue activities, and the like. The watercraft is typically equipped with an engine in an engine room in an inner space defined by a hull and a deck forming a body. The engine drives a water jet pump, which pressurizes and accelerates water sucked from a water intake generally provided on a hull bottom surface and ejects it rearward from an outlet port. As the resulting reaction, the watercraft is propelled forward.
For example, when making such a watercraft approach a position parallel to a shoreline, a driver must steer a steering handle while manipulating a throttle lever to control a propulsion force for turning the body. A conventional jet-propulsion personal watercraft is equipped with an actuator to restrict a closed position of a throttle valve subjected to a force applied from a return spring in a direction to close the throttle valve. In this watercraft, even when the throttle lever is operated to cause the throttle valve to be moved to a fully closed position during driving, the actuator restricts a closing operation of the throttle valve immediately before an engine speed reaches an idling engine speed so that the engine speed is maintained slightly higher than the idling engine speed for a certain time period. This makes it possible to delay time when the engine speed reaches the idling engine speed. As a result, the watercraft can be steered effectively for a longer time period.
However, in the above described conventional jet-propulsion personal watercraft, when the driver operates the throttle lever to close the throttle valve, the throttle valve is quickly closed under the force applied from the return spring up to a position at which the actuator restricts the closing operation of the throttle valve and then the actuator abruptly restricts the closing operation of the throttle valve. Although the driver has operated the throttle lever to close the throttle valve, the driver feels a slight acceleration operation after a lapse of some time after start of the deceleration.